Jet propulsion control system



April 7, 1964 J. E. POTTHARST, JR

JET PROPULSION CONTROL SYSTEM Filed Sept. 28. 1961 5 Sheets-Sheet l Ml TQ Q WhL his ATTORNEYS April 7, 1964 J. E. POTTHARST, JR 3,127,741

JET PROPULSION CONTROL SYSTEM Filed Sept. 28, 1961 5 Sheets-Sheet 2 INVENTOR. JOHN E. POTTHARSI JR.

BY BMBMM @wwQwb his ATTORNEYS Apnl 7, 1964 J. E. POTTHARST, JR 3,127,741

JET PROPULSION CONTROL SYSTEM Filed Sept. 28, 1961 5 Sheets-Sheet 5 FIG 3 Il'llllllllllll INVENTOR.

JOHN E. POTTHARST, JR.

BY 1 a /4M QMQW his 47' T ORNE Y5 Apnl 7, 1964 J. E. POTTHARST, JR 3,127,741

v JET PROPULSION CONTROL SYSTEM Filed Sept. 28, 1961 5 Sheets-Sheet 4 his ATTORNEYS April 7, 1964 J. E. POTTHARST, JR 3,127,741

JET PROPULSION CONTRQL SYSTEM I I d I :1 4 1'! II I ISM 'U lull ml by INVENTOR. JOHN E. POTTHARS'KJR FIG 6 BY his ATTORNEYS United States Patent Ofifice 3,127,741 Patented Apr. 7, 1964 3,127,741 .l-ET PROI ULSIDN CONTROL SYSTEM John E. Pottharst, in, 498 Northline Metairie, New @rleans, La. Filed Sept. 28, 1961, Ser. No. 141,376 9 Claims. (Q1. fill- 35.54)

This invention relates to a control system for a marine water jet propulsion unit.

The jet propulsion control system of the present inven tion includes an exhaust nozzle which communicates with the discharge of a water pump and discharges a jet stream of water at high velocity from the transom of the boat to impart forward thrust to the boat, adjustable steering rudders accommodated within the exhaust nozzle for steering the boat in the ahead direction, means upstream of the adjustable steering rudders for deflecting the jet stream of water flowing through the nozzle into a forwardly extending reverse passage for driving the boat in the astern direction, and adjustable steering rudders in the reverse M exhaust passage connected with the ahead steering rudders for steering the boat when driven in the astern direction.

The jet propulsion control system of the present invention is designed for maximum efiiciency while afiording a high degree of maneuverability to the boat. Toward this end, the jet stream deflecting means comp-rises counterbalanced reversing gates which are moved in unison in opposite directions relative to the jet stream so that the jet stream produces opposite and counterbalancing forces thereon for ease of operation. Also, the ahead steering rudders are designed so that they are balanced in their straight-ahead positions and unbalanced when they are turned in either direction from their straight-ahead positions. When they are turned in either direction from their straight-ahead positions, unbalanced forces acting on the rudders tend to return the rudders to their straightahead positions.

'In a preferred embodiment of the present invention, the ahead steering system includes at least one pair of rudders which are located with their inner surfaces substan tially in line with the walls of the jet stream passage upstream of the rudders. By virtue of this arrangement, in their straight-ahead positions, the steering rudders impose virtually no drag on the boat; moreover, the flow of the jet stream along the inner surfaces of the rudders maintains the rudders balanced in their straight-ahead positions. However, when the rudders are turned from their straight-ahead positions, the jet stream exerts unbalanced forces on the rudders which tends to return them to their straight-ahead positions.

These and other features of the present invention will be apparent by reference to the detailed description which follows and to the accompanying drawings in which:

FIGURE 1 is a plan view of a boat equipped with a jet propulsion unit embodying the control system of the present invention;

FIGURE 2 is a cross-sectional view taken on the line 2-2 of FIGURE 1, looking in the direction of the arrows;

FIGURE 3 is a cross-sectional view taken on the line 33 of FIGURE 2, looking in the direction of the arrows;

FIGURE 4 is a view similar to FIGURE 2 of an alternative embodiment of the control system;

FIGURE 5 is a plan view, partly broken away, of the embodiment shown in FIGURE 4; and

FIGURE 6 is a cross-sectional view taken on the line 6-6 of FIGURE 4, looking in the direction of the arrows.

The present invention is applicable to a marine jet propulsion unit of the type shown in FIGURE 1 in which water is drawn into an opening on the hull of the boat through an intake housing 10 and is discharged at high velocity by a propeller type pump 11 through a housing 12 containing the control system of the present invention. The pump 11 is driven by an engine 13 through a drive shaft 14. The high velocity flow discharged from the housing 12 imparts the necessary thrust to drive the boat at high speed.

The control system for the jet propulsion unit is shown in more detail in FIGURES 2 and 3 of the drawings. As shown in FIGURE 2, the housing 12 includes an upstream section 12a and a downstream section 12b bolted thereto. The upstream section 12a is provided with a flange 15 which is connected to a flange 16 of the pump housing by bolts 18.

The housing 12 contains a water flow passage 19 therethrough which communicates :at its upstream end with the discharge of the pump 11 and then tapers into a rearwardly extending exhaust nozzle. A plurality of rudders 2%} are adjustably mounted in the discharge end of the passage 19 for steering the boat when the boat is driven in the forward direction. The water is pumped through the passage 19 at high velocity and expelled from the stern transom of the boat to impart a forward thrust to the boat. The pivotal adjustment of the rudders 2 19 deflects this stream of water and changes the direction or" thrust, thereby affording steering control for the boat when the boat is driven in the forward direction.

In the embodiment shown in FIGURES 2 and 3 of the drawings, three rudders 29 are provided in the discharge end of the passage 19. The two outboard rudders when adjusted to their straight-ahead positions are substantially in line with the side Walls of the passage 19 and, therefore, are out of the path of the jet stream.

Each of the three rudders 20' is pivotally mounted on a vertical axis by a pair of pins 21 and 22,. The ups-tanding pin 21 is rotatably mounted in an upper bushing 23 of the housing section 12b, and the downwardly depending pin 22 is rotatably mounted in a lower bushing 24 of the housing section 12b. The three rudders 2a are adjusted simultaneously by the side-toside actuation of a transverse link 25 which is pivotally connected to the forward ends of forwa dly extending tiller arms 26 attached to vertical extensions 27 of each of the pins 21.

The inlets of a plurality of reversing pass-ages 3i) communicate with the passage 19 upstream of the steering rudders 20. Specifically, there are six separate reversing passage-s which, when the jet stream is deflected through them, direct six streams of water in a forwardly direction to impart a rearward thrust to the boat.

Two reversing gates 32 and 33 mounted within the passage 19 cooperate either to permit the water stream to flow rearwardly between the steering rudders 20 to impart forward thrust to the boat or deflect the jet stream into the reversing passages 30 to impart rearward thrust to the boat. Whcn these gates are adjusted to drive the boat in the forward direction, the lower gate '32 closes the inlets to the reversing passages, and the gates 32 and 33 form walls of the nozzle passage 19. When it is desired to shift the boat into reverse, both gates are operated simultaneously, the lower gate pivoting upwardly and the upper gate pivoting downwardly until they come into the edge-to-edge engagement shown in phantom lines in FIG- URE 2 of the drawings. When adjusted to edge-to-edge relationship they cooperate to define a downwardly and rearwardly sloped wall which deflects the water stream into the reversing passages 30.

As shown in FIGURE 3, the lower gate 32 is supported for pivotal movement by later-ally extending journals 3-4 accommodated in bearings 35 of the housing 12. The upper gate 33 is supported for pivotal movement in similar fashion.

The gates 32 and 33 are mechanically connected together by a parallelogram linkage arrangement so that they can be operated simultaneously through a common actuator. Toward this end, a bell crank lever 35 is connected to the gate 33, an arm 36 is aflfixed to the end of one of the journals 34 of the lower gate 32, and a connecting link 37 pivotally connects the lower end of the bell crank lever 35 with the lower end of the arm 36. The upper end of the bell crank lever 35 is connected by a pin and slot connection 38 to the lower end of a link 39 pivoted for rotation on a pin 40. The upper end of the link 39 is pivotally connected to a reverse-ahead actuating lever 41.

When the actuating lever 41 is moved to the left from the position indicated in FIGURE 2, the gates 32 and 33 are pivotally adjusted to their edge-to-edge positions shown in phantom lines in FIGURE 2 to deflect the water stream from the passages defined by the ahead rudders into the reversing passages 30 to impart reverse thrust to the boat. During this operation, the lowering of the gate 33 tends to counterbalance the lifting of the gate 32 to make for ease of operation. In addition, the increased effort to lower the upper gate 33 against the force exerted by the jet stream as the eflective surface area of the upper gate presented to the water stream increases is substantially counterbalanced by the force exerted by the jet stream tending to raise the lower gate 32 as the effective surface area of the lower gate 32 presented to the jet stream increases.

In order to afford steering control for the boat driven in the aster-n direction, each of the reverse passages 30 contains a reverse rudder 43, and these are mechanically coupled to the ahead rudders 20 so that both the ahead rudders and the reverse rudders are operated from the steering wheel of the boat. 30 are arranged in two rows of three each, three parallel shafts 44 are provided, each carrying two reverse rudders, and the three shafts are connected by a parallelogram linkage enclosed within a sealed chamber 45 of the housing 12. The shafts 44 are rotated in unison by a bevel gear 46 carried at the lower end of the pin 22 associated with the center rudder 20. The bevel gear 46 meshes with a bevel gear segment 47 carried by the centrally located shaft 44 and this bevel gear segment carries a downwardly depending arm 48 which is connected by transverse links 49 to the lower ends of downwardly depending arms 48 aflixed to the shafts 44 on either side of the centrally located shaft. Thus, the transverse link which pivotally adjusts the three ahead rudders 20 also pivotally adjusts the six reverse rudders 43.

An alternative embodiment of the control system of the present invention is shown in FIGURES 4 through 6 of the drawings. In this embodiment, the extreme end of the nozzle passage 19 flares outwardly to accommodate two ahead rudders 50. The rudders 50 are each pivotally mounted on a vertical axis by a pair of pins 51 and 52. The rudders are connected to the pins by upper and lower laterally extending plates 53 and 54, respectively. The upper end of each of the pins 51 carries a pulley 55 around which a steering cable 56 passes. The pulleys 55 are each provided with a forwardly extending tiller arm 57, and the tiller arms of the two ahead rudders 50 are connected by a transverse link 58 so that the ahead rudders 50 move in unison.

In the rudder arrangement of the embodiment shown in FIGURES 4 through 6 the rudders in the ahead direction are out of the path of the water stream with their inner surfaces forming continuations of the side walls of the exhaust passage upstream of the rudders. A feature of this arrangement is that the rudders impose virtually no drag on the boat while, at the same time, the flow of the water stream along the inner surfaces of the rudders tends to maintain them balanced in straight-ahead positions. Another feature of the rudder arrangement is that when the rudders are adjusted in one direction of the other, one of the ahead rudders presents a greater surface area to the jet stream than the other, creating an unbalanced condition which tends to restore the rudders to the straight-ahead position. More specifically, when the Since the six reverse passages rudders are in the positions shown in FIGURE 5, the downstream end of the port rudder 50 presents a larger surface area to the jet stream than the upstream end of the starboard rudder 50. Since the force of the jet stream on the port rudder tends to restore the rudders to the straight-ahead position, it is apparent that the unbalanced forces acting on the two rudders will tend to restore the steering wheel to the straight-ahead position. The effect, therefore, is very similar to that obtained with the conventional steering rudder of a propeller-driven boat.

Since in the embodiment shown in FIGURES 4 through 6 the vertical axes of the ahead rudders 50 lie in the same planes as the horizontal axes of the two shafts 44 outboard of the intermediate shaft 44, the lower ends of the pins 52 both carry bevel gears 60 which mesh with bevel gear segments 61 aflixed to the ends of the said outboard shafts 44. As shown in FIGURE 6, each of the gear segments 61 has a downwardly depending arm 62 aflixed thereto. These arms 62 are connected by links 63 to the lower end of an arm 64 afiixed to the intermediate of the shafts 44. Thus, as in the embodiment shown in FIGURES 1 through 3 of the drawings, the shafts 44 are all connected by a parallelogram linkage to rotate in unison in order to adjust the reverse rudders 43. In addition, the reverse rudders are mechanically coupled to the ahead rudders 50, and both are controlled through the steering cables 56 from the steering wheel of the boat.

The invention has been shown in preferred forms by way of example only, and many variations and modifications can be made therein without departing from the spirit of the invention. The invention, therefore, is not to be limited to any specified form or embodiment except insofar as such limitations are expressly set forth in the claims.

I claim:

1. A control for a marine jet propulsion unit comprising an exhaust passage for discharging a jet stream to impart forward thrust to the boat, means defining a reverse discharge passage for the jet stream to impartreverse thrust to the boat, a deflector gate movable from a position closing said reverse discharge passage to a position for deflecting the jet stream into the reverse passage, ahead rudder means for deflecting the jet stream discharged through the exhaust passage for steering the boat during forward propulsion, astern rudder means for deflecting the jet stream discharged through the reverse passage for steering the boat during astern propulsion and common actuating means for both the ahead and reverse rudder means.

2. A control for a marine jet propulsion unit comprising an exhaust passage for discharging a jet stream to impart forward thrust to the boat, means defining a reverse discharge passage for the jet stream to impart reverse thrust to the boat, and counterbalanced reversing gates movable in unison in opposite directions to the jet stream from open positions to positions in which they cooperate to deflect the jet stream into the reverse discharge passage, one gate moving against and the other moving with the jet stream.

3. A control for a marine propulsion unit as set forth in claim 2 including common actuating means for both reversing gates.

4. A control for a marine jet propulsion unit as set forth in claim 2 in which at least one of the reversing gates closes the reverse discharge passage when the boat is to be driven in the forward direction.

5. A control for a marine jet propulsion unit comprising a passage for discharging a jet stream to impart forward thrust to the boat, means defining a reverse discharge passage for the jet stream to impart reverse thrust to the boat, upper and lower pivotally mounted reversing gates, one movable downwardly and the other movable upwardly into edge-to-edge relationship to define a p g efle ing Wall, whereby the increased eflort to lower the upper gate against the force exerted by the jet stream as the effective area of the upper gate presented to the Water stream increases is counterbalanced at least in part by the force exerted by the jet stream tending to raise the lower gate as the effective area of the lower gate presented to the jet stream increases.

6. A control for a marine jet propulsion unit comprising a passage for discharging a jet stream to impart forward thrust to the boat, steering rudder means for deflecting the jet stream at the end of the passage for steering the boat in the forward direction, a reverse discharge passage communicating with the passage upstream of the rudder means, a pair of counterbalanced reversing gates movable into cooperating position to define a deflecting wall for directing the jet stream into the reverse discharge passage to impart reverse thrust to the boat, rudder means in the reverse discharge passage connected to the rudder means at the end of the said passage, and common activating means for imparting movement to the reversing gates.

7. A control for a marine jet propulsion unit as set forth in claim 6 in which the reverse discharge passage is subdivided into a plurality of passages and including a rotatable shaft extending through a plurality of said reverse discharge passages, the shaft supporting a reverse rudder within each of the reverse discharge passages.

8. A control for a marine jet propulsion unit as set forth in claim 6 in which the rudder means for steering the boat in the forward direction includes connected rudders mounted so that the trailing end of one and the upstream end of the other turns into the jet stream for steering, the area of the trailing end being larger than the area of the upstream end to produce unbalanced forces which tend to return the rudders to the forward position.

9. A marine jet propulsion system comprising means defining an exhaust passage through which a jet stream is discharged to impart forward thrust to a vessel, said exhaust passage defining means including a pair of side walls, at least two steering rudders at opposite sides of said exhaust passage, the leading edge of each rudder in the straight-ahead position of the rudder being directly behind and in substantial alignment with a downstream edge of one of the side walls of the exhaust passages, means pivotally mounting each rudder on an axis intermediate the leading and trailing edge of the rudder, whereby the pivotal movement of the rudder in one direction moves the leading end of the rudder away from the opposite edge of the respective side wall and into the path of the jet stream, causing part of the jet stream to be deflected outwardly between the rudder and the downstream edge of the respective side wall, and the pivotal movement of the rudder in the opposite direction moves the trailing end of the rudder into the path of the jet stream, means for pivotally moving the rudders in unison from their straight-ahead positions to move the leading end of one rudder and the trailing end of the other rudder into the jet stream, the trailing: end of the rudder presented to the jet stream being of greater effective area than the leading end of the other rudder presented to the jet stream, whereby an unbalanced force is exerted on the rudders by the jet stream which tends to restore them to their straight-ahead positions, walls defining a reverse discharge passage communicating with the exhaust passage upstream of the rudders, means for deflecting the jet stream into the reverse discharge passage for propulsion astern, and rudder means for deflecting the jet stream flowing through the reverse discharge passage and operatively coupled with said abovementioned rudders.

References Cited in the file of this patent UNITED STATES PATENTS 1,344,518 Rees June 22, 1920 1,493,280 Rees May 6, 1924 2,024,274 Campini Dec. 17, 1935 2,945,346 Arnzen July 19, 1960 3,040,526 Austin June 26, 1962 3,040,527 Christensen et a1. June 26, 1962 3,070,956 Christensen Jan. 1, 1963 

2. A CONTROL FOR A MARINE JET PROPULSION UNIT COMPRISING AN EXHAUST PASSAGE FOR DISCHARGING A JET STREAM TO IMPART FORWARD THRUST TO THE BOAT, MEANS DEFINING A REVERSE DISCHARGE PASSAGE FOR THE JET STREAM TO IMPART REVERSE THRUST TO THE BOAT, AND COUNTERBALANCED REVERSING GATES MOVABLE IN UNISON IN OPPOSITE DIRECTIONS TO THE JET STREAM FROM OPEN POSITIONS TO POSITIONS IN WHICH THEY COOPERATE TO DEFLECT THE JET STREAM INTO THE REVERSE DISCHARGE PASSAGE, ONE GATE MOVING AGAINST AND THE OTHER MOVING WITH THE JET STREAM. 